This invention relates to gas turbines and more particularly to the analysis of a pulsation signal derived from the combustion of fuel in the turbine. The pulsation signal is an indication of the fuel burning efficiency within the silo combustor.
During the operation of gas turbines, a pulsation signal derived from the fuel combustion within the silo combustor of a gas turbine can be monitored to detect efficiency, degradation and optimize cleaning intervals. The pulsation signal is monitored during turbine operation and alarm and trip signals are generated based on exceeding thresholds.
The prior art has shown that the analysis and signal conditioning of the pulsation signal can be performed with a combination of analog and digital technology. It is, however, desirable that the analysis and signal conditioning of the pulsation signal be performed solely by digital means as digital analysis and signal conditioning has advantages not only in manufacture but also in performance. The method of the present invention provides that digital analysis and signal conditioning.
A method for analyzing and conditioning the analog pulsation signal derived from combustion of fuel in a turbine. The method has the following steps:
(a) converting the analog pulsation signal to a digital signal;
(b) digitally filtering the digital signal;
(c) providing from the digitally filtered digital signal a digital value which is the true RMS value of a user defined predetermined frequency band of the analog pulsation signal;
(d) determining if an alarm output is on;
(e) determining when an alarm output is not on if the digital true RMS value is greater than a predetermined alarm limit;
(f) incrementing an alarm timer when the digital true RMS value is greater than the predetermined alarm limit; and
(g) outputting an alarm when the count in the alarm timer is greater than a predetermined accumulated time.
A method for analyzing and conditioning the analog pulsation signal derived from combustion of fuel in a turbine. The method has the following steps:
(a) converting the analog pulsation signal to a digital signal;
(b) digitally filtering the digital signal;
(c) providing from the digitally filtered digital signal a digital value which is the true RMS value of a user defined predetermined frequency band of the analog pulsation signal;
(d) determining if an alarm output is on;
(e) determining when the alarm output is not on if the digital true RMS value is greater than a user defined predetermined alarm limit; and
(f) determining if an alarm counter has a count greater than zero when the digital true RMS value is not greater than the predetermined alarm limit.
A method for analyzing the analog pulsation signal derived from combustion of fuel in a turbine. The method has the following steps:
(a) converting the analog pulsation signal to a digital signal;
(b) digitally filtering the digital signal;
(c) providing from the digitally filtered digital signal a digital value which is the true RMS value of a user defined predetermined frequency band of the analog pulsation signal;
(d) determining if an alarm output is on; and
(e) determining when the alarm output is on if the digital true RMS value is less than a predetermined limit.
A method for analyzing the analog pulsation signal derived from combustion of fuel in a turbine. The method has the following steps:
(a) converting the analog pulsation signal to a digital signal;
(b) digitally filtering the digital signal;
(c) providing from the digitally filtered digital signal a digital value which is the true RMS value of a user defined predetermined frequency band of the analog pulsation signal;
(d) determining if at least one of a plurality of predetermined conditions exist to stop processing of the digital true RMS value; and
(e) stopping processing of the true digital RMS value when at least one of the plurality of predetermined conditions exist.
An apparatus for analyzing an analog pulsation signal derived from combustion of fuel in a turbine. The apparatus has:
(a) means for converting the analog signal to a digital signal;
(b) a digital signal processor for digitally filtering the digital signal and providing therefrom a digital value of a user defined predetermined frequency band of the analog pulsation signal;
(c) a digital processor; and
(d) a routine executed by the digital processor for:
(i) determining if an alarm output is on;
(ii) determining when an alarm output is not on if the digital true RMS value is greater than a user defined predetermined alarm limit;
(iii) incrementing an alarm timer when the digital true RMS value is greater than the predetermined alarm limit; and
(iv) outputting an alarm when the count in the alarm timer is greater than a predetermined accumulated time.